Storage arrangement for highly volatile liquids



S. 5. SMITH Aug. 9, 1960 STORAGE ARRANGEMENT FOR HIGHLY VOLATILE LIQUIDSFiled Feb. 21, 1956 3 Sheets-Sheet 1 BY F HTTX

Aug. 9, 1960' S. 5. SMITH STORAGE ARRANGEMENT FOR HIGHLY VOLATILELIQUIDS Filed Feb. 21, 1956 3 Sheets-Sheet 2 s. s. SMITH Aug. 9, 1960STORAGE ARRANGEMENT FOR HIGHLY VOLATILE LIQUIDS Filed Feb. 21, 1956 3Sheets-Sheet 3 liquid state.

change on the stored products.

creases the pressures within the storing tanks.

STORAGE ARRANGEMENT FOR HIGHLY VOLATILE LIQUIDS Sydney S. Smith,Scarsdale, N.Y., assignor,.by mesne assignments, to Union Tank CarCompany, Chicago, 111., a corporation of New Jersey Filed Feb. 21, 1956,Ser. No. 566,812 1 Claim. 01. 137-263) The invention relates to anarrangement adapted to receive and store highly volatile liquids such asliquefied petroleum and the like. I

The use of liquefied petroleum has rapidly grown in recent years.Particularly, the increased acceptance of liquefied petroleum by usersin large urban markets'has increased the demand, said usershavingheretofore avoided such use because of certain dangerouscharacteristics of the product. To satisfy this increased demand, waysto increase the volume of product transported from the source of the rawmaterial to the remote large consumer areas are being explored. Usually,liquefied petroleum is transported in tank cars, trucks, barges, or thelike. It has long been obvious to many persons familiar with theindustry, that such methods of transport did not lend themselves toquick volume distribution and reduced costs. Accordingly, cross-countrypipe lines have been and are being utilized to provide the high rate andvolume transport of these products. As a'rezift of this means oftransport, many problems have arisen and the industry has long felt theneed for a storage arrange ment which would satisfy these problems andaid in ren den'ng the pipe line method of transport economical.

The problems mentioned revolve generally around the nature of liquefiedpetroleum 'product and the resulting difficulties in handling.Considering, for example, the liquefied petroleum product known aspropane, it is'well known that it will boil and evaporate at normaltemperatures and pressures which makes it difficult to move in the Theuse of the pipe line method of transportation requires that the productbe moved under pressure and at high rates per unit of time. Thesefactors make the reception of the product, both at way stations alongthe pipe line route and receiving depots, an extremely difficult andcostly problem. Storage facilities of flexible nature must be provided.That is, the facilities must have the capacity to receive and store theliquid under pressure at high pipe line rates, and additionally saidfacilities must have the capacity to eject the stored liquid into pipeline at similarly high rates under pressure. Further, the storagefacilities, to render them commercially feasible, must also be easilyadaptable to slow reception and ejection of the liquid. It is thereforeseen that the storage facility must lend itself to any combination ofslow and fast reception and ejection of product as the requirements of aparticular installation may demand.

Further problems are also presented because of the fact that liquids ofthis nature must be kept under'pressure. The facilities designed reflectthis fact and must also take into account the effect of climatictemperature For example, normal heating resulting from action of the sunconsiderably in- I It is also well known that products of this kind havecertain dangerous characteristics, such as high volatility which in turnresults in inherent fire and explosion hazards. Therefore,

2,948,294 Patented Aug. 9, 1960 2 fire protection is. an importantconsideration in the design of any storage facilities for this type ofproduct.

. With the above in mind, it has been found that the initialconstruction expense and up keep costs of storage stations heretoforeused for products of this type, has

adversely affected transport of this type product in pipe lines and theindustry has long been searching for economical ways to reduce thesecosts and aid in making the pipe line method of transport commerciallyattractive.

Accordingly, it is a primary object of this invention to provide anarrangement particularly adapted to the reception, storage and ejectionof liquefied petroleum products and the like, that is both economical inconstruction and upkeep costs and sufiiciently flexible to accommodatethe various requirements of present day product distribution methods.Particularly, the invention comprehends, in general, a storagearrangement having a plurality of main storage compartments locatedunderground and comprising a plurality of separate tanks novelty andcommonly manifolded so as to accommodate high and low rate productacceptance and discharge in combination with an ejection standpipe orpressure tank andprotective venting, the latter protecting thearrangement against excessive high vapor pressure as well as liquidoverflow.

, It has been found that the arrangement herein disclosed is extremelyeconomical from the standpoint of initial cost and further issufficiently flexible to meet the requirements of input stations, waystations, or final depots. Additionally, the system offers adequateprotective features from the standpoint of corrosion, fire andexplosion.

It, will also be understood that the arrangement disclosed isparticularly advantageous to certain industrial users in that it willafford him flexibility fromthe stand-' point of types of productsstorable. That is, the user, if he so desires, can use certaintanks inthe battery to store one type of productand use others to'store entirelydilferent type of products and can thereafter selectibly discharge fromthe desired tanks and avoid any possibility of intermixing.

Theseand other objects of the invention will be more clearly understoodfrom an examination of the followline 5-5 of Figure 2, a I

Figure 6 is a detail view of the standpipe employed in the invention,and

Figure 7 is a schematic view of the piping arrangement associated withthe standpipe.

Describing the invention in detail and directing attention to Figures 1and 2, it will be seen that the storage arrangement comprises aplurality of cylindrical, elongated tanks, indicated generally at 2. Thetanks 2 are preferably located underground, that is,themajor portionsthereof are covered with earth fill, such as is illustrated at 4 inFigure 3. In view of the ease of shop fabrication, each tank 2 ispreferably cylindrical in crosssection and is provided with dished heads6, 6 at the opposite ends thereof. Additionally, the tanks 2 may beconstructed of slightly different diameters, whereby pairs of tanks maybe telescoped one within the the other to reduce shipping costs from thepoint of shop fabrication to the point of field construction.

Centrally of each tank 2, a manway 8 is provided, said manway extendingto a point immediately above the surface of the fill 4-. A sump 10 ispositioned on each tank 2 centrally thereof and at a point immediatelybelow the manway 8. It will be understood that the tank 2 is providedwith a slight downward taper from the ends 6, 6 to the sump 11?, wherebyliquid in the tank will normally be urged by gravity to -flow toward thesump 10. It is desirable and necessary that the product, when deliveredto the consumer, be dry. The-product, when deposited in the storagesystem may be and frequently is contaminated with water, such as, forexample, salt water incident to salt dome storage at the producing site.Occasionally water from the pipe line itself, which is incident to and aresult of the use of the pipe line to ship products of varying kind,will also find its way to the storage tanks. This water, being heavierthan the liquefied petroleum product will move to the bottom of the tankwhereat the central taper feature will carry it to the bottom of thesump 10 for removal. To accommodate such removal, there is provided aclosable water drain line 13 which extends downwardly into each sump 10to the bottom thereof at a point substantially below the pump 23. Atdetermined intervals, the station operator may sample each tank 2 forthe presence of water, and, if such water is found in any tank, it couldbe removed via line 13.

A main line 12, which may be connected (not shown) to a cross-countrypipe line, is arranged to communicate with a common fill header 14, saidfill header 14 extending transversely of the long axis of the tanks 2.Each tank 2 has a fill line 16 internally thereof and arranged to extendin a generally parallel relationship to the long axis of said tank andadjacent the upper limit thereof. The fill line 16 may be provided witha plurality of discharge apertures 18 formed in the circumferencethereof, as is best shown in Figure 5. It will be understood that theapertures 18 are preferably distributed along the entire length of theline 16. This arrangement assures an even distribution of incomingproduct to various sections of the tank and in eifect sprays theincoming product over a large area in the tank. This important featureof spraying the incoming fluid results in a stabilization of pressure atthe vapor pressure of the product in the tank in view of the fact that alarge portion of the vapor in the tank is absorbed and returned toproduct as the volume of the tank becomes filled with liquid. Thereafterthe pressure within the tank remains constant regardless of the amountof product in the tank. Therefore, the amount of product in vapor formthat may be vented to atmosphere during filling is eliminated, except inthe rare event that the vapor pressure of the liquid at the temperaturereceived in the tanks exceeds the pressure setting of the relief valveof the system, a contingency that can be controlled.

Each fill line 16 communicates with an incoming pipe 20 which in turncommunicates with the common fill header 14. It will be noted that eachline 20 has provided therein a gate valve 22 to selectively open orclose communication between the header 14 and the related fill line -16.a

A discharge pump 23 is preferably located in the sump 10 whereby itssuction side will be constantly flooded with product. A pump dischargeline 26 extends upwardly from the sump 10 and encloses a drive shaftfrom the pump motor 24, as is best seen in Figures 3 and 4. Thedischarge side of the pump 23 communicates with the line 27 which inturn communicates with a common discharge header 28. It will beparticularly noted that each tank 2 is provided with an individual pump23, said pumps 23 discharging to the common header 28. Each line 27 maybe provided with a gate valve 3t? as well as a one way check valve 32,the latter accommodating flow to the discharge header 28 only.

A vertical pressure tank 34 is preferably located at a point centrallyof the "battery of tanks 2, said tank 34 communicating with the commondischarge header 28 and arranged to receive the product therefrom. Afloat controlled valve 35 is in the line between the discharge header 28and the tank 34 to close communication therebetween in the event thatthe tank becomes full. A pump out line 36 communicates with the lowerend of the tank 34 and the suction side of a variable capacity pump 38.The discharge .sideof the pump 38 may then be connected (not shown) witha pump out line which may be selectably connectable to a pipe line orother distribution facilities. v 1

Returning to Figures 1 and 2 it will be seen that each tank 2 isprovided with ports" 40, and 42 adjacent the opposite ends thereof.Considering the ports .0, it will be noted that they communicate with acommon header 44, said header 44 communicating with a line 46 which maybe open to the atmosphere. The line 46 has aconventional rupture valve48 located therein. This particular structure is desirable in the eventthat one of the tanks becomes filled with product without manual orautomatic shut off operation (hereinafter described). It will be notedthat any liquid overflow is accommodated by the header 44 and that theliquid will be carried to other tanks 2 in the battery that have notbeen filled. In the event that the entire battery of the tanks 2 arefilled to capacity and a particular shut off fails to operate, the valve48 may be arranged to rupture under appropriate liquid pressure andaccommodate escape of the liquid through the line 46 which may carry theliquid to a safe disposal area.

Considering the other end of the tanks 2, it will be noted that theports 42 on each tank are also arranged to communicate with a commonheader 50, said common header 50 is connected with a line 52 which mayextend to an appropriate flare stack (not shown) or the like. A reliefvalve 54 may be located in the line 52 and arranged to open under theaction of a predetermined vapor pressure. Thus, if for some reason, thevapor pressure in the battery of tanks 2 should rise to an unsafe levelthe valve 54 will open and accommodate the escape of said pressure atsome point Where it can be safely burned off.

Directing attention to Figures 2 and 3, it will be seen that a liquidlevel indicator and control line 60 is arranged to extend downwardlyfrom the top of the manway 8 into the sump ltl immediately adjacent thepump line 26. The liquid level arrangement (not shown in detail) may beof any conventional variety employed by those skilled in the art todetermine the level of the liquid in a particular tank. For example, aconventional electronic level indicator may be employed, said indicatortranslating the level information in a particular tank to a plurality ofdials (not shown) which may be located at a central control station 62(Figure 1). In the alternative, a conventional float type indicator (notshown) may also be used to furnish the same information.

In normal operation of the arrangement, it is desirable on initialfilling, to clear each tank 2 o f air therein. This may be accomplishedby opening lines 52 and 46 upon initial entrance of the propane into thetank. Thus, it will be understood that the fluid is delivered throughpipe 12 to the header 14 and distributed from the header 14 concurrentlyto each lead line 20, from whence it is conducted to the fill line 16,whereat it is sprayed internally throughout each tank. The liquid, beingvaporized at normal pressure, will immediately set up a vapor pressurewithin the tank. Because the opposed ends 6 of the tank are at a higherlevel than the central portion thereof, the air will be urged by thevapor in the tank and escape through the ports 40, 42 and the lines 46and 52. After initial air purging, the lines 52 and 48 may be closed andit can be safely assumed that all of the air in the tank has beeneliminated and the non-liquid occupying space therein will thereafter befilled entirely by the product in the vapor phase. Thereafter uponentrance or exit of product in the tank, the pressure in the tank willremain virtually constant at just about the vapor pressure of the liquidregardless of the quantity of liquid in a given tank.

It will also be understood that the particular arrangement of the fillline 12 and manifold 14 communicating in parallel with the battery oftanks 2, will be such as will accommodate a high entrance rate ofproduct, that is, the arrangement will accommodate the high productrates normally found in pipe line transportation. As each tank becomesfull, the associated valve 22 may be manually or automatically shut offuntil the entire battery of tanks 2 is completely full of product. Atthis point product entrance through line 12 is halted. When it isdesired to empty the tanks, and particularly where it is desired toreturn the product to a pipe line having product therein moving at ahigh pipe line rate, it is necessary to open the valves 30 and start thepumps 23, whereby each tank discharges into the discharge header 28,which in turn carries the product to and fills the vertical pressuretank 34. The tank 34 is necessary to assure that the suction side of thepump 38, which discharges the product to the pipe line, will beconstantly flooded with product. As each tank approaches a predeterminedempty condition, the related pump is shut off leaving the tank incondition to again receive and store product.

The particular arrangement of the individual pumps 23 and common header28 and the tank 34 will enable the product stored in the tanks 2 to bedischarged to the pipe line under proper pressure and at product ratescomplementing the high pipe line rates. Thus, it will be understood thatthe arrangement described is peculiarly adapt able to the storage andretransmission of highly volatile liquids which are transportedcross-country in pipe lines. Additionally, the tanks 2 may receiveproduct even though it is transmitted through pipe 12 at relatively lowrates, as may be found where product is transported by barge or railwaycar. Further, because each tank is equipped with an individual pump 23that can be operated independently, discharge to line 36 can be handledat relatively low rates. Additionally, individual tanks in the batterycan be separately discharged.

Thus, it will be seen that the disclosed storage arrangement is readilyadaptable to and solves the problems incident to the low costtransportation of highly volatile liquids from producing areas toconsuming areas. It will further be understood that because of theunderground disposition of the tanks, the tanks 2 may be designed withconsiderably thinner wall sections, and still withstand vapor pressureof the contained liquid. Further, the underground disposition of thetanks substantially shields the tanks from climatic action andtemperature change which may result in extremely high vapor pressuresdue to excessive heating. In addition, the fire hazard associated withthis arrangement is considerably reduced because a leak in a tank cannotbe supplied with oxygen needed to support fire until the product makesits way to the soil surface whereat it may burn without transmitting anunreasonable amount of heat back to the tanks.

Those familiar with the art will additionally appreciate the featurethat all tank connections, manifolds, headers and the like are locatedabove ground (Figures 1, 3 and 4) while the main storage tanks are belowground. This avoids the possibility of underground leakage which mayresult from tank and/or foundation settling with attendant unknownproduct loss. Further, if a leak or some other accident should affect atank or its associated connection that tank can readily be isolated andproduct thereafter can be received into or ejected from the remainingtanks in the battery. The individual controllable output pump on eachtank is one of the features responsible for this desirable arrangement.

It will be understood that the invention as shown is by way ofillustration and not limitation and that it may be subject to variousmodifications Without departing from the spirit thereof or the scope ofthe appended claim.

What is claimed is:

In a receiving, storage and dispensing arrangement for volatile liquid,the combination of a plurality of separate elongated product tanksdisposed underground, a pump associated with each tank and including aninlet means communicating with the bottom of said tank, said tank beingin graded relationship to said pump inlet means to accommodate gravityliquid flow to its pump inlet means, an intake manifold having aconnection to a product source, a first line communicating with eachtank and each line having a connection to the manifold, each line havingindependently operated stop valve means, a discharge header, a secondline communicating with each tank at its pump outlet means and eachhaving a connection to the discharge header, each of said pumps beingoperative to deliver liquid from its tank to the header under pres- 1sure, a check valve in each of said second lines accommodating flow fromthe tank to the header only, other independently operated stop valvemeans in each of the second lines, a pressure tank above the ground, afirst conduit establishing communication between the discharge headerand the pressure tank, control valve means in the first conduit toselectively close said last mentioned communication, a second conduithaving a connection to the pressure tank, variable capacity pump meansoperatively associated with the second conduit to evacuate product fromthe pressure tank at selectible varying rates, and pressure relief meansincluding a second header in communication with each of the undergroundtanks, a third conduit communicating with said second header andextending above the ground, and means operable in response to apredetermined pressure in the third conduit for venting said tanks.

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